Fertilization of ovules and the initiation of seed development lead to hormone production that triggers fruit development. Consequently, fruits usually contain seeds, but seeds can form without fertilization (parthenogenesis), and fruits can develop without seeds (parthenocarpy). Many fruits that are cooked or eaten as part of a main course are usually classed as vegetables. This dichotomy is reflected in the origins of the two words: fruit, from the Latin fruor, “to enjoy,” and vegetable, from the Latin vegetare, “to enliven.”
Ecology of Fruits
In nature, fleshy fruits serve as a reward for seed dispersing animals. In keeping with the evolutionary principle that selection tends to minimize the cost of structures while maximizing their function, the flesh of these fruits contains comparatively few calories and basically consists of colored, flavored sugar water. Using animals as dispersal agents carries a risk, however, of seed destruction. Consequently, fleshy fruits that are dispersed by animals exhibit a number of mechanisms that protect seeds. One of these is the production of a large, hard seed that an animal cannot eat, such as a peach pit or a mango seed. Another protective characteristic is small seeds that go through an animal’s digestive system without being crushed or digested, such as strawberry seeds. Over the last ten thousand years that humans have been practicing agriculture, many fleshy fruited species have been domesticated and bred for improved fruit production and quality. Several of the most marketed fruits worldwide are discussed below.
The rose family (Rosaceae) contains a wide array of fruits grown in the cool regions of the world: apples, pears, plums, peaches, cherries, strawberries, and raspberries.